user
Write a response that appropriately completes the request.

### Instruction:
How is nuclear energy generated?

### Response:
assistant
Nuclear energy is generated through the use of nuclear reactions to release energy. In nuclear reactors, the energy is released when atoms are split apart, or when they combine to form new, heavier atoms. Fission, the splitting of an atom, is the most common type of reaction used to create energy, while fusion, the joining of two atoms, is less common but produces more energy. Nuclear energy is used to generate electricity and to power ships, submarines, and spacecraft.